Latexes with phosphoric acid functional resin particles

ABSTRACT

Latex compositions are provided. In embodiments, a latex comprises water and resin particles. The resin particles comprise a polymerization product of reactants comprising one or more types of hydrophobic monomers and one or more types of acidic monomers comprising one or more types of phosphoric acid monomers, wherein a total amount of polymerized acidic monomers in the resin particles is at least about 8 weight % and a total amount of polymerized phosphoric acid monomers in the resin particles is at least about 2 weight %.

BACKGROUND

Aqueous inkjet ink compositions often include water, water-dispersiblecolorants, hydrophilic solvents, and binding resins. Binding resinsenhance the durability and coating properties of the inks. They are alsoused to adjust and control the viscosity of the ink to achieve suitablejetting performance. Some binding resins have also been developed toadsorb, attach, or form a coating on the colorants in order to improvethe stability and dispersibility of the colorants within the inks.

SUMMARY

The present disclosure provides latexes which may be used to provideresin particles for a variety of compositions such as aqueous inkjet inkcompositions. The resin particles are polymerized from hydrophobicmonomers and acid monomers, including phosphoric acid monomers. Whenincorporated into aqueous inkjet ink compositions, the inks exhibitsurprisingly high stabilities as evidenced by little to no change inviscosity after long-time storage at elevated temperatures (e.g., 14days at 60° C.). Aqueous inkjet ink compositions comprising embodimentsof the resin particles also exhibit extended open-air stability,facilitating the collection of waste ink from open-air waste trays ofaqueous inkjet systems. Embodiments of the resin particles also provideaqueous inkjet ink compositions exhibiting high adhesion to a variety ofsubstrates, including excellent water fastness. These advantages areachieved regardless of the type of colorant being used and even withoutthe resin particles being adsorbed, attached, or coated onto thecolorant. Finally, embodiments of the resin particles provide“universal” aqueous inkjet ink compositions that are able to form highquality printed images on a broad range of paper and non-paper, e.g.,metal substrates.

Latex compositions are provided. In embodiments, a latex comprises waterand resin particles. The resin particles comprise a polymerizationproduct of reactants comprising one or more types of hydrophobicmonomers and one or more types of acidic monomers comprising one or moretypes of phosphoric acid monomers, wherein a total amount of polymerizedacidic monomers in the resin particles is at least about 8 weight % anda total amount of polymerized phosphoric acid monomers in the resinparticles is at least about 2 weight %.

Other principal features and advantages of the disclosure will becomeapparent to those skilled in the art upon review of the followingdrawings, the detailed description, and the appended claims.

DETAILED DESCRIPTION

Latex

In one aspect, latexes are provided. Such a latex comprises resinparticles synthesized from various monomers, forming a polymericmaterial from which the resin particles are composed. Hydrophobicmonomers are used to form the resin particles. Various hydrophobicmonomers may be used such as styrene; alkyl (meth)acrylates, such as,methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate,dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, methylmethacrylate, ethyl methacrylate and butyl methacrylate; β-carboxy ethylacrylate (β-CEA), phenyl acrylate, methyl alphachloroacrylate;butadiene; isoprene; methacrylonitrile; acrylonitrile; vinyl ethers,such as vinyl methyl ether, vinyl isobutyl ether, and vinyl ethyl ether;vinyl esters, such as vinyl acetate, vinyl propionate, vinyl benzoateand vinyl butyrate; vinyl ketones, such as vinyl methyl ketone, vinylhexyl ketone and methyl isopropenyl ketone; vinylidene halides, such asvinylidene chloride and vinylidene chlorofluoride; N-vinyl indole;N-vinyl pyrrolidone; methacrylate; acrylamide; methacrylamide;vinylpyridine; vinylpyrrolidone; vinyl-N-methylpyridinium chloride;vinyl naphthalene; p-chlorostyrene; vinyl chloride; vinyl bromide; vinylfluoride; ethylene; propylene; butylenes; and isobutylene. (The use of“(meth)” as in, e.g., “(meth)acrylic acid”, refers to both acrylic acidand methacrylic acid.) A single type or combinations of different typesof hydrophobic monomers may be used. The phrase “single type” refers tosame chemical compounds whereas the phrase “different types” refers todifferent chemical compounds. For example, styrene is a single type ofhydrophobic monomer while styrene and alkyl (meth)acrylates aredifferent types of hydrophobic monomers. Methyl (meth)acrylate is asingle type of hydrophobic monomer (specifically, a single type of alkyl(meth)acrylate) while methyl (meth)acrylate and ethyl (meth)acrylate aredifferent types of hydrophobic monomers (specifically, different typesof alkyl (meth)acrylates). Thus, the phrase “one or more types”encompasses both monomers of a single type and monomers of differenttypes.

In embodiments, the hydrophobic monomers used to form the resinparticles comprise styrene, an alkyl (meth)acrylate (e.g., methyl(meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, orcombinations thereof), or both. Thus, the alkyl group of the alkyl(meth)acrylates may have 1 or more carbons, 2 or more carbons, 4 or morecarbons, or from 1 to 6 carbons.

In embodiments, certain hydrophobic monomers are not used to form theresin particles, including 4-methylstyrene, cyclohexyl acrylate,isobornyl methacrylate, isobornyl acrylate, or combinations thereof.

Acidic monomers are also used to form the resin particles, includingphosphoric acid monomers. The phosphoric acid monomers are polymerizablemonomers that have a polymerizable moiety (e.g., a carbon-carbon doublebond) as well as a P(O)(OR)₃ moiety. The polymerizable moiety may beprovided by the R group. In the P(O)(OR)₃ moiety, each R may beindependently selected from a hydrogen and an organic group, wherein atleast one R is the organic group. The term “phosphoric acid” is usedsince the P(O)(OR)₃ moiety is closely related to phosphoric acid,P(O)(OH)₃, having three hydroxyl groups. The phosphoric acid monomerused may have 1, 2, or 3 such organic groups, which may be the same ordifferent. Salts of the phosphoric acid monomer are also encompassed,i.e., in which the hydrogen of an OH group is replaced by a cation. TheP(O)(OR)₃ moiety is distinguished from a phosphonic acid moieties havingformula P(O)(OR)₂R.

In embodiments, the organic group is an alkyl (meth)acrylate. Inembodiments, the alkyl group of the alkyl (meth)acrylate has at least 2carbons, at least 3 carbons, at least 4 carbons, at least 5 carbons, orfrom 1 to 6 carbons. In embodiments, at least one R is ethyl(meth)acrylate. In embodiments, the phosphoric acid monomer has 1, 2, or3 ethyl (meth)acrylate groups. Illustrative phosphoric acid monomersinclude phosphoric acid 2-hydroxyethyl methacrylate ester andbis[2-(methacryloyloxy)ethyl] phosphate.

In embodiments, the organic group has Formula I

wherein R₁₋₃ are independently selected from hydrogen and methyl; n isfrom 0 to 20, including any number between 0 and 20; and “*” denotes thebond to an oxygen of the P(O)(OR)₃ moiety. In embodiments, n is 0, R₁ ishydrogen or methyl, and R₃ is hydrogen. One, two, or three such organicgroups may be present.

In embodiments, the phosphoric acid monomer is based on poly(ethyleneglycol) wherein in Formula I, R₁ is hydrogen or methyl, R₂ is hydrogen,R₃ is hydrogen and n is from 0 to 20. In embodiments, n is from 1 to 20.This includes from 2 to 16 and from 4 to 12. Although one, two, or threesuch organic groups may be present. In embodiments, one such organicgroup is present to provide a phosphate ester of poly(ethylene glycol)mono(meth)acrylate (i.e., the other R groups are hydrogen).

In embodiments, the phosphoric acid monomer is based on poly(propyleneglycol) wherein in Formula I, R₁ is hydrogen or methyl, R₂ is methyl, R₃is methyl and n is from 0 to 20. In embodiments, n is from 1 to 20. Thisincludes from 2 to 16 and from 4 to 12. Although one, two, or three suchorganic groups may be present. In embodiments, one such organic group ispresent to provide a phosphate ester of poly(propylene glycol)mono(meth)acrylate (i.e., the other R groups are hydrogen).

Although other organic groups may be used, in embodiments, the organicgroup is not vinyl (i.e., CH₂CH₂).

A single type or combinations of different types of phosphoric acidmonomers may be used. (The meaning of “single type,” “different types,”and “one or more types” is analogous to that described above forhydrophobic monomers.)

In addition to the phosphoric acid monomers, other acidic monomers maybe used to form the resin particles. These other acidic monomers referto those of a different type, i.e., a different chemical compound, ascompared to the selected phosphoric acid monomers and which do not havethe P(O)(OR)₃ moiety described above. Thus, these other acidic monomersmay be referred to as “additional acidic monomers.” The additionalacidic monomers which may be used include (meth)acrylic acid monomers,sulfonic acid monomers, sulfonate monomers, and combinations thereof.Illustrative acidic monomers include acrylic acid, methacrylic acid,ethacrylic acid, dimethylacrylic acid, maleic anhydride, maleic acid,styrenesulfonic acid, vinylsulfonate, cyanoacrylic acid, vinylaceticacid, allylacetic acid, ethylidineacetic acid, propylidineacetic acid,crotonoic acid, fumaric acid, itaconic acid, sorbic acid, angelic acid,cinnamic acid, styrylacrylic acid, citraconic acid, glutaconic acid,aconitic acid, phenylacrylic acid, acryloxypropionic acid, aconiticacid, phenylacrylic acid, acryloxypropionic acid, vinylbenzoic acid,N-vinylsuccinamidic acid, mesaconic acid, methacroylalanine,acryloylhydroxyglycine, sulfoethyl methacrylic acid, sulfopropyl acrylicacid, styrene sulfonic acid, sulfoethylacrylic acid,2-methacryloyloxymethane-1-sulfonic acid,3-methacryoyloxypropane-1-sulfonic acid, 3-(vinyloxy)propane-1-sulfonicacid, ethylenesulfonic acid, vinyl sulfuric acid, 4-vinylphenyl sulfuricacid, vinyl benzoic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid,and combinations thereof. As with the phosphoric acid monomers, theseadditional acidic monomers also encompass salts thereof. Similarly, asingle type or combinations of different types of additional acidicmonomers may be used. (The meaning of “single type,” “different types,”and “one or more types” is analogous to that described above forhydrophobic monomers.)

In embodiments, additional acidic monomers are used along with thephosphoric acid monomers. In embodiments, the additional acidic monomerscomprise (meth)acrylic acid, β-CEA, or both. As further described below,the use of additional acidic monomer (along with the phosphoric acidmonomers) and in the amounts described below is useful to improve thestability of aqueous inkjet ink compositions formed from the disclosedlatexes.

A variety of other monomers may be used to form the resin particles. Forexample, a monomer which is an ester of (meth)acrylic acid with analcohol comprising a dioxane moiety or an alcohol comprising a dioxolanemoiety may be used. In the present disclosure, this type of monomer maybe referred to as an “dioxane/dioxolane monomer.” This phrase,dioxane/dioxolane monomer, encompasses the monomer which is the ester of(meth)acrylic acid with the alcohol comprising the dioxane moiety, themonomer which is the ester of (meth)acrylic acid with the alcoholcomprising the dioxolane moiety, and both such monomers. The dioxanemoiety may be a 1,3-dioxane moiety and the dioxolane moiety may be a1,3-dioxolane moiety. The alcohol comprising the dioxane/dioxolanemoiety may be an acetal of a triol, a ketal of a triol, or a carbonateof a triol. Illustrative triols include glycerol and trimethylolpropane.The triol may be unsubstituted or substituted. By “substituted” it ismeant that one or more bonds to a carbon(s) or hydrogen(s) are replacedby a bond to non-hydrogen and non-carbon atoms. The dioxane/dioxolanemonomer may have Formula II (dioxane) or III (dioxolane) as shown below,wherein R is selected from hydrogen and methyl; R′ is selected fromhydrogen and ethyl; and Z is selected from hydrogen, an oxygen of acarbonyl group, an alkyl group, an aryl group, and an alkoxy group.Either or both types of monomers may be used in the resin particles.

The carbonyl group refers to a C═O group, that is Z is O covalentlybound to the carbon via a double bond, thereby forming a carbonyl groupbetween the two oxygens of the 5 or 6-membered ring. The alkyl group maybe linear or branched. The alkyl group may have from 1 to 20 carbons.This includes having from 1 to 18 carbons and from 1 to 10 carbons,e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbons. The alkyl group may besubstituted or unsubstituted. The aryl group may be monocyclic havingone aromatic ring, e.g., benzene, or polycyclic having one or more fusedrings. The aryl group may be unsubstituted or substituted as describedabove with respect to the alkyl group, although substituted aryl groupsalso encompass aryl groups in which a bond to a hydrogen(s) is replacedby a bond to an unsubstituted or substituted alkyl group as describedabove. The alkoxy group refers to an —O-alkyl group.

Illustrative dioxane/dioxolane monomers include glycerol formal(meth)acrylate, trimethylolpropane formal (meth)acrylate, andisopropylideneglycerol (meth)acrylate. A single type or combinations ofdifferent types of dioxane/dioxolane monomers may be used. Inembodiments, however, the dioxane/dioxolane monomer is glycerol formal(meth)acrylate. Glycerol formal (meth)acrylate has a relatively highT_(g) (about 85-90° C.). In the present disclosure, the name “glycerolformal (meth)acrylate” (as well as the names of the otherdioxane/dioxolane monomers described in this paragraph) refers to eitherthe dioxane isomer, the dioxolane isomer, or both. That is, allpossibilities are encompassed by the names.

Although not necessary, in some embodiments, multifunctional monomers,i.e., those comprising more than one polymerizable group (e.g., 2, 3,4), may be used to form the resin particles. (The term “multifunctionalmonomer” is a term distinguished from a phosphoric acid monomers thatmay contain more than one polymerizable group.) Multifunctional monomersare useful as they facilitate crosslinking within the resin particles.Illustrative multifunctional monomers include difunctional monomers suchas a poly(ethylene glycol) di(meth)acrylate, e.g., poly(ethylene glycol)diacrylate having a molecular weight of 250 g/mol. Other poly(ethyleneglycol) di(meth)acrylates may be used, including those having amolecular weight in a range of from 214 g/mol to 1000 g/mol, from 214g/mol to 500 g/mol, and from 214 g/mol to 300 g/mol. These molecularweight values may be determined using gel permeation chromatography.Other difunctional monomers include a diacrylate compound bonded with analkyl chain containing an ether bond, such as diethylene glycoldiacrylate, triethylene glycol diacrylate, tetraethylene glycoldiacrylate, polyethylene glycol #400 diacrylate, polyethylene glycol#600 diacrylate, dipropylene glycol diacrylate, and compounds obtainedby substituting acrylate of these compounds with methacrylate; adiacrylate compound bonded with a chain containing an aromatic group andan ether bond, such aspolyoxyethylene(2)-2,2-bis(4-hydroxyphenyl)propane diacrylate,polyoxyethylene(4)-2,2-bis(4-hydroxyphenyl)propane diacrylate, andcompounds obtained by substituting acrylate of these compounds withmethacrylate. Other difunctional monomers include a diene compound, suchas isoprene and butadiene, an aromatic divinyl compound, such asdivinylbenzene and divinylnaphthalene; a diacrylate compound bonded withan alkyl chain, such as ethylene glycol diacrylate, 1,3-butylene glycoldiacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate,1,6-hexanediol diacrylate, 1,10-dodecanediol diacrylate, neopentylglycol diacrylate, and compounds obtained by substituting acrylate ofthese compounds with methacrylate. Multifunctional monomers includepentaerythritol triacrylate, trimethylolmethane triacrylate,trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate,oligoester acrylate, and compounds obtained by substituting acrylate ofthese compounds with methacrylate.

In embodiments, however, the monomers which are used to form the resinparticles do not include multifunctional monomers, e.g., polyfunctionalacrylates. Similarly, in embodiments, crosslinking agents, e.g., epoxidecontaining compounds, are not used to form the resin particles.

Reactive surfactants may be used to form the resin particles. Suitablereactive surfactants comprise a polymerizable (and thus, reactive) groupsuch that they become incorporated into the resin particles.Illustrative reactive surfactants include anionic ether sulfate reactivesurfactants such as those in the commercially available Hitenol seriessuch as Hitenol AR10-25. Other suitable reactive surfactants includepolyoxyethylene alkylphenyl ether ammonium sulfate, Hitenol BC-10,BC-20, BC10-25, BC-2020, BC-30; polyoxyethylene styrenated phenyl etherammonium sulfate including Hitenol AR-10, AR-20, AR-2020; non-ionicpolyoxyethylene alkylphenyl ether including Noigen RN-10, RN-20, RN-30,RN-40, RN-5065; and reactive surfactant available from Ethox includingE-sperse RX-201, RX-202, RX-203, RS-1596, RS-1616, RS-1617, RS-1618,RS-1684.

A chain transfer agent may be used to form the resin particles. Thechain transfer agent may be a mercaptan or a thiol. Suitable chaintransfer agents include n-dodecylmercaptan (NDM), n-dodecanethiol (DDT),tert-dodecylmercaptan, 1-butanethiol, 2-butanethiol, octanethiol, andcombinations thereof. Halogenated carbons such as carbon tetrabromide,carbon tetrachloride, and combinations thereof may be used as chaintransfer agents.

In embodiments, other certain monomers are excluded in forming the resinparticles. Monomers which may be excluded are unsaturated ethylenemonomers having an alkyl group having from 12 to 22 carbons.

In forming the latex comprising the resin particles, variouscombinations of the monomers described above may be used in a monomeremulsion comprising a solvent. Water is generally used as the solvent,but water-soluble or water-miscible organic solvents (e.g., ethanol) mayalso be included. The type of monomers and their relative amounts may beselected to tune the properties of the resin particles/latex, includingto achieve the values of the properties described below. Illustrativeamounts are provided below.

The total amount of hydrophobic monomers used in the monomer emulsionmay be in a range from 70 weight % to 97 weight %, from 75 weight % to90 weight %, or from 80 weight % to 90 weight %. (Here, weight % refersto the (total weight of hydrophobic monomers)/(total weight of monomersin the monomer emulsion, excluding the reactive surfactants)*100). Whenpresent, the alkyl (meth)acrylate (e.g., methyl (meth)acrylate, ethyl(meth)acrylate), butyl (meth)acrylate) may be present at an amount of atleast 15 weight %, at least 20 weight %, at least 25 weight %, or in arange of from 15 weight % to 30 weight %. (Weight % has a meaninganalogous to that described for hydrophobic monomers.)

The total amount of acidic monomers used in the monomer emulsion may beat least 8 weight %, at least 10 weight %, or at least 15 weight %. Inembodiments, the total amount of acidic monomers is less than 15 weight% or less than 10 weight %. These ranges encompass amounts from 8 weight% to 25 weight %, from 8 weight % to 20 weight %, from 10 weight % to 18weight %, and from 10 weight % to 16 weight %. (Weight % has a meaninganalogous to that described for hydrophobic monomers.) The total amountof phosphoric acid monomers used in the monomer emulsion may be at least2 weight %, at least 3 weight %, or at least 4 weight %. In embodiments,the total amount of phosphoric acid monomers is less than 10 weight % orless than 8 weight %. These ranges encompass amount from 2 weight % to10 weight %, from 2 weight % to 8 weight %, and from 2 weight % to 6weight %. (Weight % has a meaning analogous to that described forhydrophobic monomers.) As noted above, in embodiments, an additionalacidic monomer is used in addition to the phosphoric acid monomer. Insuch embodiments, a weight ratio of the total amount of the phosphoricacid monomers to the total amount of the additional acidic monomers is1.0 or less, less than 0.9, less than 0.8, less than 0.7, less than 0.6,less than 0.5, less than 0.4, or in a ratio of from 0.3 to 1.0, 0.3 to0.8, or 0.3 to 0.5.

If a dioxane/dioxolane monomer is used in the monomer emulsion, thetotal amount of dioxane/dioxolane monomers may be in a range of from 1weight % to 40 weight %, 1 weight % to 30 weight %, 1 weight % to 20weight %, from 1 weight % to 10 weight %, and from 1 weight % to 5weight %. (Weight % has a meaning analogous to that described forhydrophobic monomers.)

If a multifunctional monomer is used in the monomer emulsion, the totalamount of multifunctional monomers may be in a range of from 0.001weight % to 1 weight %, from 0.001 weight % to 0.8 weight %, and from0.01 weight % to 0.6 weight %. (Weight % has a meaning analogous to thatdescribed for hydrophobic.)

If a reactive surfactant is used in the monomer emulsion, the totalamount of reactive surfactant may be in a range of from 0.1 weight % to6.5 weight %. (Here, weight % refers to the (total weight of reactivesurfactants)/(total weight of monomers in the monomer emulsion,including the reactive surfactant monomers)*100). This range includesfrom 0.3 weight % to 5 weight %.

The chain transfer agent(s) may be present in the monomer emulsion andmay be used in various suitable amounts, for example, from 0.25 weight %to 2.5 weight %. (Here, weight % refers to the (total weight of chaintransfer agents)/(total weight of monomers in the monomer emulsion,excluding the reactive surfactants)*100.)

In embodiments, the monomer emulsion comprises (or consists of) asolvent, hydrophobic monomers and acidic monomers, including phosphoricacid monomers. In embodiments, the hydrophobic monomers comprise styreneand an alkyl (meth)acrylate, e.g., butyl acrylate. In embodiments, thephosphoric acid monomers comprise those having formula P(O)(OR)₃,wherein each R is independently selected from a hydrogen and an organicgroup, wherein at least one R is the organic group. In embodiments, theorganic group is an alkyl (meth)acrylate. In embodiments, the organicgroup has Formula I. In embodiments, the phosphoric acid monomerscomprise phosphoric acid 2-hydroxyethyl methacrylate ester,bis[2-(methacryloyloxy)ethyl] phosphate, or a combination thereof. Inembodiments, the phosphoric acid monomers comprise a phosphate ester ofpolyethylene glycol mono(meth)acrylate, a phosphate ester ofpolypropylene glycol mono(meth)acrylate, or a combination thereof. Inany of these embodiments, an additional acidic monomer may be used,e.g., methacrylic acid. In any of these embodiments, a dioxane/dioxolanemonomer may be used (e.g., glycerol formal methacrylate). In any ofthese embodiments, a multifunctional monomer may be used (although insome embodiments, no multifunctional monomer is used). In any of theseembodiments, a reactive surfactant (e.g., an anionic ether sulfate) maybe used. In any of these embodiments, a chain transfer agent may beused. In any of these embodiments, amounts of the various monomers,reactive surfactants, and chain transfer agents may be used as describedabove. The balance may be made up of the solvent.

In embodiments, the monomer emulsion is free of (i.e., does notcomprise) a surfactant. However, in other embodiments, a surfactant maybe used. Here, “surfactant” refers to non-reactive, non-polymerizableanionic surfactants such as sodium dodecylsulfate (SDS), sodiumdodecylbenzene sulfonate, sodium dodecylnaphthalene sulfate; dialkylbenzenealkyl sulfates; palmitic acid; alkyldiphenyloxide disulfonate;and branched sodium dodecyl benzene sulfonate. “Surfactant” also refersto non-reactive, non-polymerizable cationic surfactants such asalkylbenzyl dimethyl ammonium chloride, dialkyl benzenealkyl ammoniumchloride, lauryl trimethyl ammonium chloride, alkylbenzyl methylammonium chloride, alkyl benzyl dimethyl ammonium bromide, benzalkoniumchloride, cetyl pyridinium bromide, trimethyl ammonium bromide, halidesalts of quarternized polyoxyethylalkylamines, and dodecylbenzyltriethyl ammonium chlorides. “Surfactant” also refers to non-reactive,non-polymerizable nonionic surfactants such as polyoxyethylene cetylether, polyoxyethylene lauryl ether, polyoxyethylene octyl ether,polyoxyethylene octylphenyl ether, polyoxyethylene oleyl ether,polyoxyethylene sorbitan monolaurate, polyoxyethylene stearyl ether,polyoxyethylene nonylphenyl ether, dialkylphenoxy poly(ethyleneoxy)ethanol, and block copolymer of polyethylene oxide and polypropyleneoxide.

In embodiments, the monomer emulsion is free of (i.e., does notcomprise) silica particles. Commercially available silica particleswhich may be excluded are the following: various grades of LUDOXColloidal Silica such as FM, SM, HS-30, HS-40, LS, TM-40, TM-50, SM-AS,AS-30, AS-40, AM, HSA, TMA, P X-30, P t-40, P W-50, CL, and CL-P; andvarious grades of Nissan Chemical Silica such as SNOWTEX ST-20L, ST-30,ST-40, ST-50, ST-OS, ST-O, ST-O-40, ST-OL, ST-C, ST-C-30, ST-CM, ST-N,STN30G, ST-N40, ST-NS, ST-XS, ST-S, ST-UP, ST-O-UP, MA-ST-UP, ST-PS-S,AMT-3305, HX-305M1, and HX-305M5.

Various polymerization techniques may be used to form the resinparticles such as monomer-starved emulsion polymerization, conventionalemulsion polymerization, suspension polymerization, mini-emulsionpolymerization, nano-emulsion polymerization, seeded-emulsionpolymerization, and microemulsion polymerization. These polymerizationtechniques may make use of any of the monomer emulsions described above.An illustrative monomer-starved emulsion polymerization process isdescribed below. It is noted, however, that the polymerization techniqueused provides the polymerized polymer in the form of particles which areinsoluble in aqueous media. This is by contrast to polymerizationtechniques, e.g., solution polymerization, including those described inU.S. Pat. No. 9,963,592, which provide solubilized polymers in organicmedia.

An illustrative method of making a latex comprising the resin particlescomprises adding any of the monomer emulsions described above to areactive surfactant solution at a feed rate over a period of time. Thereactive surfactant solution comprises a solvent and a reactivesurfactant. Any of the solvents and any of the reactive surfactantsdescribed above may be used. The reactive surfactant in the reactivesurfactant solution may be the same type or a different type as comparedto a reactive surfactant that may be present in the monomer emulsion.The reactive surfactant solution may further comprise a buffer. Variousbuffers may be used such as sodium bicarbonate, sodium carbonate, andammonium hydroxide. The reactive surfactant may be used in an amount ina range of from 0.1 to 10 weight % and from 0.5 weight % to 5 weight %.(Here, weight % refers to the (total weight of reactivesurfactants)/(total weight of reactive surfactant solution)*100.) Thebuffer may be used in an amount in a range of from 0.25 weight % to 2.5weight %. (Weight % has a meaning analogous to that described above.)

An initiator may be included in the reactive surfactant solution.Alternatively, a separate initiator solution comprising the initiatorand any of the solvents described above may be formed and the separateinitiator solution added to the reactive surfactant solution. Theseparate initiator solution may be added prior to the addition of themonomer emulsion. An additional amount of a separate initiator solutionmay be added after the addition of the monomer emulsion. Examples ofsuitable initiators include water soluble initiators, such as ammoniumpersulfate (APS), sodium persulfate and potassium persulfate; andorganic soluble initiators including organic peroxides and azo compoundsincluding Vazo peroxides, such as VAZO 64™, 2-methyl 2-2′-azobispropanenitrile, VAZO 88™, 2-2′-azobis isobutyramide dehydrate; andcombinations thereof. Other water-soluble initiators which may be usedinclude azoamidine compounds, for example2,2′-azobis(2-methyl-N-phenylpropionamidine) dihydrochloride,2,2′-azobis[N-(4-chlorophenyl)-2-methylpropionamidine]di-hydrochloride,2,2′-azobis[N-(4-hydroxyphenyl)-2-methyl-propionamidine]dihydrochloride,2,2′-azobis[N-(4-amino-phenyl)-2-methylpropionamidine]tetrahydrochloride,2,2′-azobis[2-methyl-N-(phenylmethyl)propionamidine]dihydrochloride,2,2′-azobis[2-methyl-N-2-propenylpropionamidine]dihydrochloride,2,2′-azobis[N-(2-hydroxy-ethyl)2-methylpropionamidine]dihydrochloride,2,2′-azobis[2(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride,2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride,2,2′-azobis[2-(4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl)propane]dihydrochloride,2,2′-azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane]dihydrochlo-ride,2,2′-azobis[2-(5-hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl)propane]di-hydrochloride,2,2′-azobis {2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane}dihydrochloride, and combinations thereof. The initiator may be used inan amount in a range of from 0.05 weight % to 2.5 weight %. (Here,weight % refers to the (total weight of initiators)/(total weight ofreactive surfactant solution)*100.)

In embodiments, the reactive surfactant solution comprises (or consistsof) a solvent (e.g., water), a reactive surfactant, and optionally, oneor more of an initiator and a buffer. In any of these embodiments,amounts of the reactive surfactants, initiator, and buffer may be usedas described above. The balance may be made up of the solvent. At leastin some embodiments, the reactive surfactant solution is free of (i.e.,does not comprise) any of the surfactants described above. In at leastsome embodiments, the reactive surfactant solution is free of (i.e.,does not comprise) any of the silica particles described above. As aresult, the resin particles may be characterized as being free of (i.e.,not comprising) any of the surfactants and/or any of the silicaparticles described above. In at least some embodiments, the reactivesurfactant solution is free of (i.e., does not comprise) any monomers,other than the reactive surfactant monomer(s) present in the solution.

The addition of the monomer emulsion to the reactive surfactant solutionmay be carried out under an inert gas (e.g., nitrogen) and at anelevated temperature (e.g., greater than room temperature such as atemperature in a range of from 50° C. to 90° C.). This may beaccomplished by purging with the inert gas and heating the reactivesurfactant solution prior to the addition of the monomer emulsion andcontinuing during the addition of the monomer emulsion.

As noted above, the monomer emulsion is added at a feed rate over aperiod of time. In the presence of the initiator, the monomers of themonomer emulsion undergo polymerization reactions to form the resinparticles of the latex. The feed rate is sufficiently slow so that thepolymerization is carried out under “monomer-starved” conditions. Thismeans that the feed rate is no greater than the rate the polymerizationreactions, e.g., between styrene and acrylate monomers. Illustrativefeed rates include those in a range of from 1 mL/min to 10 mL/min basedon a total reaction volume of 1 L. Illustrative periods of time includethose in a range of from 60 minutes to 600 minutes. After the monomeremulsion has been added, the polymerization may be allowed to continuefor an additional period of time, with or without the addition ofadditional initiator. Illustrative additional periods of time includethose in a range of from 1 hour to 18 hours. Both the addition of themonomer emulsion and the polymerization after addition may be carriedout under the inert gas and at the elevated temperature. Optionally, thelatex formed may be processed by standard techniques such ascoagulation, dissolution and precipitation, filtering, washing, ordrying. The processed or unprocessed latex may be used to form theaqueous inkjet ink compositions described below.

The monomer-starved emulsion polymerization process described above doesnot involve the use of a resin seed in forming the resin particles.However, as noted above, seeded-emulsion polymerization techniques maybe used.

The methods may further comprise forming the monomer emulsion, formingthe reactive surfactant solution, and/or forming the initiator solution.Each may be formed by combining the desired components at the desiredamounts and mixing.

The composition of the resin particles depends upon the selection of themonomers and their relative amounts, as well as the polymerizationreactions between selected monomers that produce a polymerizationproduct as described above. Thus, a variety of compositions areencompassed, including those based on various polymerization products ofreactants comprising various combinations of monomers. As noted above,the reactants include hydrophobic monomers and acidic monomers includingphosphoric acid monomers, but otherwise, the selection of other monomersis not particularly limited. For clarity, the composition of the resinparticles may be identified by reference to the monomers which arepolymerized, recognizing that the chemical form of those monomers isgenerally altered as a result of the polymerization reactions. Oncepolymerized in the resin particles, monomers may be referred to as“polymerized monomers.”

In embodiments, the resin particles comprise (or consist of) thepolymerization product (e.g., copolymer) of reactants comprisinghydrophobic monomers and acidic monomers, including phosphoric acidmonomers. In embodiments, the hydrophobic monomers comprise styrene andan alkyl (meth)acrylate, e.g., butyl acrylate. In embodiments, thephosphoric acid monomers comprise those having formula P(O)(OR)₃,wherein each R is independently selected from a hydrogen and an organicgroup, wherein at least one R is the organic group. In embodiments, theorganic group is an alkyl (meth)acrylate. In embodiments, the organicgroup has Formula I. In embodiments, the phosphoric acid monomerscomprise phosphoric acid 2-hydroxyethyl methacrylate ester,bis[2-(methacryloyloxy)ethyl] phosphate, or a combination thereof. Inembodiments, the phosphoric acid monomers comprise a phosphate ester ofpolyethylene glycol mono(meth)acrylate, a phosphate ester ofpolypropylene glycol mono(meth)acrylate, or a combination thereof. Inany of these embodiments, an additional acidic monomer may be used,e.g., methacrylic acid. In any of these embodiments, a dioxane/dioxolanemonomer may be used (e.g., glycerol formal methacrylate). In any ofthese embodiments, a multifunctional monomer may be used (although insome embodiments, no multifunctional monomer is used). In any of theseembodiments, a reactive surfactant (e.g., an anionic ether sulfate) maybe used. In each of these embodiments, an initiator (or a portionthereof) may be incorporated at an end of each polymer chain in theresin particles. In each of these embodiments, the resin particles maybe crosslinked. In each of these embodiments, the polymerized monomersmay be present in the resin particles in the amounts described abovewith respect to the amounts of monomers in the monomer emulsion. This isbecause experiments have shown that the conversion of the monomersduring the polymerization reactions is above 99.9%. For example, thetotal amount of polymerized acidic monomers in the resin particles maybe in a range of from 8 weight % to 25 weight %. Analogous to thedefinition of weight % provided above, when referring to the resinparticles, the term weight % refers to (total weight of polymerizedacidic monomers)/(total weight of polymerized monomers, excludingpolymerized reactive surfactants)*100).

Using a specific, illustrative composition, the composition of the resinparticles may also be identified as poly[(styrene)-ran-(butylacrylate)-ran-(phosphoric acid 2-hydroxyethyl methacrylateester)-ran-(methacrylic acid)-ran-(anionic ether sulfate)]. In thisdescription, the different chemical moieties which result from thepolymerization reactions is identified by reference to the correspondingmonomer in its parenthesis and “ran” refers to the random incorporationof the different monomers into the copolymer. The use of thisdescription encompasses the presence of an initiator (or portionthereof) at the beginning of each copolymer as well as crosslinking (ifused).

In embodiments in which certain monomers (or other reactants) areexcluded from forming the resin particles, it follows that such monomers(or other reactants) do not participate in the polymerization reactionsto form the polymeric matrix of the resin particles. Thus, in theseembodiments, the composition of the resin particles may be described asbeing free of (i.e., not comprising) one or more of 4-methylstyrene,cyclohexyl acrylate, isobornyl methacrylate, isobornyl acrylate, and anunsaturated ethylene monomer having an alkyl group having from 12 to 22carbons.

In embodiments, the latex may be described as being free of (i.e., notcomprising) a resin/polymer other than what is provided by the resin ofthe present resin particles themselves.

Since the resin/polymer making up the resin particles has already beenpolymerized, the latex itself is generally not curable and as such, isfree of (i.e., does not comprise) an initiator. This does not precludethe presence of a minor amount of unreacted initiator or reactedinitiator which may be incorporated into polymer chains. Similarly, thelatex may be described as being free of (i.e., not comprising) monomers.

In embodiments, the latex may also be described as being free of (i.e.,not comprising) components such as a boric acid, diglycolic acid, achelating agent (e.g., ethylenediaminetetraacetic acid (EDTA)), orcombinations thereof. In this embodiment, exclusion of a chelating agentdoes not refer to excluding the phosphoric acid monomer (which ispolymerized into the resin particles).

The latex itself may also distinguished from the aqueous inkjet inkcompositions described herein (and similar compositions) by notcomprising a colorant (including any of the colorants described below).

The water content of the latexes may be at least 40 weight %. Thisincludes at least 50 weight % and at least 60 weight %. These weight %refer to the weight of water as compared to the total weight of thelatex.

The resin particles may be characterized by their size. The size of theparticles may be reported as a D₅₀ particle size, which refers to adiameter at which 50% of the sample (on a volume basis) is comprised ofparticles having a diameter less than said diameter value. The D₅₀particle size may be measured using a Malvern Zetasizer Nano ZS. Forcheck of light scattering techniques and methods, NIST polystyreneNanosphere control samples having a diameter within the range of 20 nmto 200 nm available from Microspheres-Nanospheres (a Corpuscular companyof Microtrac) or third-party vendors (such as ThermoFisher Scientific)may be used. In embodiments, the resin particles are characterized by aD₅₀ particle size of from 50 nm to 120 nm. This includes from 60 nm to110 nm, and from 70 nm to 100 nm.

Latexes comprising the present resin particles may be characterized bytheir viscosities. The viscosity values may refer to a particulartemperature and a particular solids content and may be measured using aTuning fork vibration viscometer (Cole-Parmer). In embodiments, theviscosity at room temperature and a solids content of 40% is in a rangeof from 40 cp to 600 cp. This includes from 65 cp to 575 cp, 90 cp to550 cp, and from 115 cp to 525 cp. These viscosities are all initialviscosities, measured within a day of forming the latex.

The present resin particles may also be characterized by their T_(g)values. The T_(g) values may be measured using a Differential ScanningCalorimetry (DSC) TA Instruments Discovery DSC 2500. In embodiments, theT_(g) is in a range of from 40° C. to 100° C. This includes from 50° C.to 90° C., and from 60° C. to 80° C.

Aqueous Inkjet Ink Compositions

Any of the resin particles/latexes described above may be used toprovide an aqueous inkjet ink composition. By “aqueous inkjet inkcomposition,” it is meant that the composition is configured for use in,and is capable of being used in, an inkjet printing apparatus to formprinted images, as further described below. Resin particles may bepresent in the aqueous inkjet ink composition in an amount in a range offrom 1 weight % to 10 weight % and from 5 weight % to 10 weight %.(Here, weight % refers to the (total weight of resin particles)/(totalweight of aqueous inkjet ink composition)*100.) This range includes from5 weight % to 10 weight %. A variety of other components may be used toform the aqueous inkjet ink compositions as described below.

Solvent System

The aqueous inkjet ink compositions comprise a solvent system based onwater. The solvent system can consist solely of water, or can comprise amixture of water and a water-soluble and/or water-miscible organicsolvent. The water-soluble and water-miscible organic solvents may bereferred to herein as a co-solvent or a humectant. Suitable such organicsolvents include alcohols and alcohol derivatives, including aliphaticalcohols, aromatic alcohols, diols, glycol ethers, polyglycol ethers,long chain alcohols, primary aliphatic alcohols, secondary aliphaticalcohols, 1,2-alcohols, 1,3-alcohols, 1,5-alcohols, ethylene glycolalkyl ethers, propylene glycol alkyl ethers, methoxylated glycerol, andethoxylated glycerol. Illustrative examples include ethylene glycol,propylene glycol, diethylene glycols, hexyl glycol, glycerine,dipropylene glycols, trimethylolpropane, 1,2-hexanediol,1,5-pentanediol, 2-methyl-1,3-propanediol,2-ethyl-2-hydroxymethyl-1,3-propanediol, 3-methoxybutanol,3-methyl-1,5-pentanediol, 1,3-propanediol, 1,3-butanediol,1,4-butanediol, and 2,4-heptanediol. Other suitable solvents includeamides, ethers, urea, substituted ureas such as thiourea, ethylene urea,alkylurea, alkylthiourea, dialkylurea, and dialkylthiourea, carboxylicacids and their salts, such as 2-methylpentanoic acid,2-ethyl-3-propylacrylic acid, 2-ethyl-hexanoic acid, 3-ethoxyproponic,acid, and the like, esters, organosulfides, organosulfoxides, sulfones(such as sulfolane), carbitol, butyl carbitol, cellusolve, ethers,tripropylene glycol monomethyl ether, ether derivatives, hydroxyethers,amino alcohols, ketones, N-methylpyrrolidinone, 2-pyrrolidinone,cyclohexylpyrrolidone, amides, sulfoxides, lactones, polyelectrolytes,methyl sulfonylethanol, imidazole, 1,3-dimethyl-2-imidazolidinone,betaine, sugars, such as 1-deoxy-D-galactitol, mannitol, inositol, andthe like, substituted and unsubstituted formamides, and substituted andunsubstituted acetamides. Combinations of these organic solvents may beused.

Suitable water-soluble and/or water-miscible organic solvents include aglycol of hydrocarbons having a carbon number of 4 to 7. Examples ofsuch a glycol include 1,2-pentanediol; 1,2-hexanediol; 1,5-pentanediol;1,6-hexanediol; 3-methyl-1,3-butanediol; 1,2-butanediol;2,4-pentanediol; 1,7-heptanediol; 3-methyl-1,5-pentanediol;trimethylolpropane; ethyleneurea; 1,2,6-hexantriol; 1,2,3-butanetriol;sorbitol; diethylene glycol; 1,2,4-butanetriol; glycerol; diglycerol;and triethylene glycol;.

In embodiments, the solvent system comprises water, a 1,2-alcohol (e.g.,1,2-hexanediol, 1,4-butanediol, or both), a glycol (e.g., propyleneglycol), and a glycerol.

In solvent systems comprising water and an organic solvent, the water toorganic solvent weight ratio, as well as the type and relative amount ofdifferent organic solvents, may be selected to achieve certainproperties for the aqueous inkjet ink composition such as a desiredsurface tension, viscosity, etc. In embodiments, the water to organicsolvent weight ratio is from 90:10 to 51:49. If more than one organicsolvent is used, these weight ratios refer to the total amount oforganic solvent. As water may be present in the latex, colorant, etc.,these weight ratios refer to the total amount of water.

Similarly, various total amounts of the solvent system may be used inthe aqueous inkjet ink compositions. In embodiments, the solvent systemis present in an amount of from 50 weight % to 95 weight %, from 60weight % to 90 weight %, or from 65 weight % to 90 weight %. (Here,weight % refers to the (total weight of solvent system)/(total weight ofaqueous inkjet ink composition)*100.) In embodiments, the total amountof water present is at least 50 weight %, at least 60 weight %, at least70 weight %, at least 80 weight %, or in a range of from 50 weight % to95 weight %. (Here, weight % refers to the (total weight ofwater)/(total weight of aqueous inkjet ink composition)*100.)

Colorant

The aqueous inkjet ink compositions comprise a colorant. As such, theaqueous inkjet ink compositions cannot be described as being clear orcolorless. Colorants include pigments, dyes, and combinations thereof.Examples of suitable dyes include anionic dyes, cationic dyes, nonionicdyes, and zwitterionic dyes. Specific examples of suitable dyes includeFood dyes such as Food Black No. 1, Food Black No. 2, Food Red No. 40,Food Blue No. 1, Food Yellow No. 7, FD & C dyes, Acid Black dyes (No. 1,7, 9, 24, 26, 48, 52, 58, 60, 61, 63, 92, 107, 109, 118, 119, 131, 140,155, 156, 172, 194), Acid Red dyes (No. 1, 8, 32, 35, 37, 52, 57, 92,115, 119, 154, 249, 254, 256), Acid Blue dyes (No. 1, 7, 9, 25, 40, 45,62, 78, 80, 92, 102, 104, 113, 117, 127, 158, 175, 183, 193, 209), AcidYellow dyes (No. 3, 7, 17, 19, 23, 25, 29, 38, 42, 49, 59, 61, 72, 73,114, 128, 151), Direct Black dyes (No. 4, 14, 17, 22, 27, 38, 51, 112,117, 154, 168), Direct Blue dyes (No. 1, 6, 8, 14, 15, 25, 71, 76, 78,80, 86, 90, 106, 108, 123, 163, 165, 199, 226), Direct Red dyes (No. 1,2, 16, 23, 24, 28, 39, 62, 72, 236), Direct Yellow dyes (No. 4, 11, 12,27, 28, 33, 34, 39, 50, 58, 86, 100, 106, 107, 118, 127, 132, 142, 157),Reactive Dyes, such as Reactive Red Dyes (No. 4, 31, 56, 180), ReactiveBlack dyes (No. 31), Reactive Yellow dyes (No. 37); anthraquinone dyes,monoazo dyes, disazo dyes, phthalocyanine derivatives, including variousphthalocyanine sulfonate salts, aza(18)annulenes, formazan coppercomplexes, and triphenodioxazines.

Examples of suitable pigments include black pigments, cyan pigments,magenta pigments, and yellow pigments. Pigments can be organic orinorganic particles. Suitable inorganic pigments include carbon black.However, other inorganic pigments may be suitable such as cobalt blue(CoO—Al₂O₃), chrome yellow (PbCrO₄), iron oxide, and titanium dioxide(TiO₂). Suitable organic pigments include, for example, azo pigmentsincluding diazo pigments and monoazo pigments, polycyclic pigments(e.g., phthalocyanine pigments such as phthalocyanine blues andphthalocyanine greens), perylene pigments, perinone pigments,anthraquinone pigments, quinacridone pigments, dioxazine pigments,thioindigo pigments, isoindolinone pigments, pyranthrone pigments, andquinophthalone pigments), insoluble dye chelates (e.g., basic dye typechelates and acidic dye type chelate), nitro pigments, nitroso pigments,and anthanthrone pigments such as PR168. Representative examples ofphthalocyanine blues and greens include copper phthalocyanine blue,copper phthalocyanine green, and derivatives thereof (Pigment Blue 15,Pigment Green 7, and Pigment Green 36). Representative examples ofquinacridones include Pigment Orange 48, Pigment Orange 49, Pigment Red122, Pigment Red 192, Pigment Red 202, Pigment Red 206, Pigment Red 207,Pigment Red 209, Pigment Violet 19, and Pigment Violet 42.Representative examples of anthraquinones include Pigment Red 43,Pigment Red 194, Pigment Red 177, Pigment Red 216 and Pigment Red 226.Representative examples of perylenes include Pigment Red 123, PigmentRed 149, Pigment Red 179, Pigment Red 190, Pigment Red 189 and PigmentRed 224. Representative examples of thioindigoids include Pigment Red86, Pigment Red 87, Pigment Red 88, Pigment Red 181, Pigment Red 198,Pigment Violet 36, and Pigment Violet 38. Representative examples ofheterocyclic yellows include Pigment Yellow 1, Pigment Yellow 3, PigmentYellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17,Pigment Yellow 65, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow90, Pigment Yellow 110, Pigment Yellow 117, Pigment Yellow 120, PigmentYellow 128, Pigment Yellow 138, Pigment Yellow 150, Pigment Yellow 151,Pigment Yellow 155, and Pigment Yellow 213. Such pigments arecommercially available in either powder or press cake form from a numberof sources including, BASF Corporation, Engelhard Corporation, and SunChemical Corporation. Examples of black pigments that may be usedinclude carbon pigments. The carbon pigment can be almost anycommercially available carbon pigment that provides acceptable opticaldensity and print characteristics. Carbon pigments suitable for use inthe present system and method include, without limitation, carbon black,graphite, vitreous carbon, charcoal, and combinations thereof. Suchcarbon pigments can be manufactured by a variety of known methods, suchas a channel method, a contact method, a furnace method, an acetylenemethod, or a thermal method, and are commercially available from suchvendors as Cabot Corporation, Columbian Chemicals Company, Evonik, andE.I. DuPont de Nemours and Company. Suitable carbon black pigmentsinclude, without limitation, Cabot pigments such as MONARCH® 1400,MONARCH® 1300, MONARCH® 1100, MONARCH® 1000, MONARCH® 900, MONARCH® 880,MONARCH® 800, MONARCH® 700, CAB-O-JET® 200, CAB-O-JET® 300, CAB-O-JET®450, REGAL®, BLACK PEARLS®, ELFTEX®, MOGUL®, and VULCAN® pigments;Columbian pigments such as RAVEN® 5000, and RAVEN® 3500; Evonik pigmentssuch as Color Black FW 200, FW 2, FW 2V, FW 1, FW18, FW 5160, FW 5170,Special Black 6, Special Black 5, Special Black 4A, Special Black 4,PRINTEX® U, PRINTEX® 140U, PRINTEX® V, and PRINTEX® 140V. Other pigmentsinclude CAB-O-JET 352K, CAB-O-JET 250C, CAB-O-JET 260M, CAB-O-JET 270Y,CAB-O-JET 465M, CAB-O-JET 470Y and CAB-O-JET 480V (available from CabotCorporation). Other pigments include Kodak Specialty Dispersion pigmentsavailable from Kodak, Inc. These include Specialty Black Dispersion TypeP2, Specialty Cyan Dispersion Type P2, Specialty Yellow Dispersion TypeP2, Specialty Magenta Dispersion Type P3, Specialty Black DispersionType P4, Specialty Cyan Dispersion Type P1, Specialty Magenta DispersionType P1, and Specialty Yellow Dispersion Type P1. In embodiments, thecolorant is not any of the quinacridone-based pigments disclosed in U.S.Pat. No. 9,359,522.

The above list of pigments includes unmodified pigment particulates,small molecule attached pigment particulates, self-dispersed pigmentparticulates, and polymer-dispersed pigment particulates.

In forming the aqueous inkjet ink compositions, the colorant(s) may beprovided as a colorant dispersion comprising the colorant and a solvent(e.g., water). The colorant may be in the form of a particle and have anaverage particle size of from 20 nm to 500 nm, from 20 nm to 400 nm, orfrom 30 nm to 300 nm.

Various amounts of colorant may be used in the aqueous inkjet inkcompositions. Generally, however, an amount is selected such that thetotal solids content (generally provided by the resin particles, thecolorant, and if present, a wax) of the aqueous inkjet ink compositionis from 5 weight % to 15 weight %, from 6 weight % to 12 weight %, orfrom 7 weight % to 10 weight %. (Here, weight % refers to the (totalweight of solids)/(total weight of aqueous inkjet ink composition)*100.)

A feature of at least embodiments of the aqueous inkjet ink compositionsis that the resin particles are freely dispersed in the ink as opposedto being attached to, adsorbed on, or coated onto the colorant (e.g.,pigment) of the ink. This may be confirmed by viscosity measurements.For example, the Examples below describe experiments showing that theviscosity of an illustrative aqueous inkjet ink composition remainsunchanged over extended periods of time and at elevated temperatures. By“unchanged” it is meant within ±5% of an initial viscosity value.Similarly, this may be confirmed by measurements showing that the D₅₀particle size remains unchanged over extended periods of time and atelevated temperatures (here, “unchanged” has a meaning analogous tounchanged viscosity).

Wax

The aqueous inkjet ink composition may comprise a wax. Illustrativewaxes include paraffin waxes, polyethylene waxes, polypropylene waxes,microcrystalline waxes, polyolefin waxes, montan based ester waxes andcarnauba waxes. Waxes having a melting point in a range of from 50° C.to 150° C. may be used. Nanoscale (e.g., diameter of 1000 nm or less,500 nm or less, or 100 nm or less) wax emulsions based on carnauba waxand paraffin wax may be used. Waxes from Michelman may be used (e.g.,Michem Lube 103DI, 124, 124P135, 156, 180, 182, 190, 270R, 368, 511,693, 723, 743, 743P, and 985; and Michem Emulsion 24414, 34935, 36840,41740, 43040, 43240, 44730, 47950, 48040M2, 61355, 62330, 66035, 67235,70750, 71150, 71152, 91735, 93235, 93335, 93935, and 94340). Waxes fromByk may also be used, including Aquacer 2500, Aquacer 507, Aquacer 513,Aquacer 530, Aquacer 531, Aquacer532, Aquacer 535, Aquacer 537, Aquacer539, and Aquacer 593. In embodiments, the wax is an anionic nanoscalewax emulsion such as Michem Lube 190.

Various amounts of wax may be used in the aqueous inkjet inkcompositions. Generally, however, an amount is selected such that thetotal solids content of the aqueous inkjet ink composition is from 5weight % to 15 weight %, from 6 weight % to 12 weight %, or from 7weight % to 10 weight %. (Here, weight % refers to the (total weight ofsolids)/(total weight of aqueous inkjet ink composition)*100.)

Surfactant

The aqueous inkjet ink compositions may comprise one or moresurfactants. Examples of suitable surfactants include anionicsurfactants (such as sodium lauryl sulfate (SLS), Dextrol OC-40, StrodexPK 90, ammonium lauryl sulfate, potassium lauryl sulfate, sodium myrethsulfate and sodium dioctyl sulfosuccinate series), nonionic surfactants(Surfynol® 104 series, Surfynol® 400 series, Dynol™ 604, Dynol™ 607,Dynol™ 810, EnviroGem® 360, secondary alcohol ethoxylate series such asTergitol™ 15-S-7, Tergitol™ 15-S-9, TMN-6, TMN-100x and Tergitol™ NP-9,Triton™ X-100, etc.) and cationic surfactants (Chemguard S-106A,Chemguard S-208M, Chemguard S-216M). Some fluorinated or siliconesurfactants can be used such as PolyFox™ TMPF-136A, 156A, 151N,Chemguard S-761p, S-764p, Silsurf® A008, Siltec® C-408, BYK 345, 346,347, 348 and 349, polyether siloxane copolymer TECO® Wet-260, 270 500,etc. Some amphoteric fluorinated surfactants can also be used such asalkyl betaine fluorosurfactant or alkyl amine oxide fluorosurfactantsuch as Chemguard S-500 and Chemguard 5-111. Other surfactants which maybe used include Surfynol PSA 336, Surfynol SE-F, and Surfynol 107L.

Various amounts of surfactant may be used in the aqueous inkjet inkcompositions. In embodiments, the surfactant is present in an amount ina range of from 0.01 weight % to 2 weight %. (Here, weight % refers tothe (total weight of surfactant)/(total weight of aqueous inkjet inkcomposition)*100.) If more than one type of surfactant is used, theseamounts refer to the total amount of surfactant.

Additives

Various additives may be used in the aqueous inkjet ink compositions totune the properties thereof. Suitable additives include one or more ofbiocides; fungicides; stabilizers; pH controlling agents such as acidsor bases, phosphate salts, carboxylates salts, sulfite salts, aminesalts, buffer solutions; anti-foam agents; defoamers; and wettingagents. However, generally, no chelating agents (e.g., EDTA) areincluded.

Various amounts of the additives may be used in the aqueous inkjet inkcompositions. In embodiments, the additives are present in an amount ina range of from 0.01 weight % to 5 weight %. (Here, weight % refers tothe (total weight of additives)/(total weight of aqueous inkjet inkcomposition)*100.) If more than one type of additive is used, theseamounts refer to the total amount of additives.

In embodiments, the aqueous inkjet ink compositions are free of (i.e.,do not comprise) a chelating agent.

Aqueous inkjet ink compositions based on the present resin particles donot necessarily require the addition of an additive to further adjustviscosity. This can mean that the aqueous inkjet ink compositions may befree of (i.e., do not comprise) a water-soluble resin or emulsion, awater-borne binder, a polymeric dispersant, and combinations thereof.This includes the possible exclusion of any of the water-soluble resinor emulsions, water-borne binders, polymeric dispersants describedbelow. However, it is understood that in some embodiments, suchcompounds may be included. Finally, it is noted that none of the termswater-soluble resin, water-soluble emulsion, water-borne binder, andpolymeric dispersant encompass the present resin particles themselves.Illustrative water-soluble resins/emulsions are polyethylene glycol andpolyvinylpyrrolidone.

Illustrative water-borne binders are Rhoplex I-1955, Rhoplex I-2426D,Rhoplex I-62, Rhoplex I-98, Rhoplex E-1691, available from Rhohm & Haas.Others include Lucidene 190, Lucidene 400, and Lucidene 243, availablefrom DSM Corporation; NeoCryl A-1110, NeoCryl A-2092, NeoCryl A-639,NeoRad R-440, NeoRad R-441, NeoRez N-55 under the name 972, PVP K-15,PVP K-30, PVP K-60, PVP K-85, Ganex P-904LC, PVP/VA W-63 available fromISP. Other exemplary water-borne binders include those available fromJohnson Polymers (BASF) such as Joncryl 537, Joncryl H538, Joncryl H538.

Illustrative polymeric dispersants are acrylic polymers such asstyrene-acrylic copolymers and vinylpyrrolidone copolymers, urethane orpolyurethane dispersions, and acrylic-urethane hybrid dispersions. Morespecific polymeric dispersants include those available from JohnsonPolymers (BASF) such as Joncryl® 671, Joncryl® 683, Joncryl® 296,Joncryl® 690, Joncryl HPD 296, Joncryl HPD96-E, Joncryl LMV 7085,Joncryl 8082. Other dispersants include those described in EP Patent No.2097265, which is incorporated by reference for purposes of thedispersants, and those described in U.S. Patent Application No.2019284414, which is incorporated by reference for purposes of thedispersants.

Similarly, the aqueous inkjet ink compositions may be free of (i.e., donot comprise) a resin other than those provided by the resin of thepresent resin particles. A single type of resin may be used. Similarly,the aqueous inkjet ink composition itself is generally not curable andas such, is free of (i.e., does not comprise) an initiator. It is notedthat any other exclusions referenced above with respect to the resinparticles and latex may be applied to embodiments of the aqueous inkjetink compositions.

In embodiments, an aqueous inkjet ink composition comprises (or consistsof) a solvent system; resin particles; a colorant; and optionally, oneor more of a wax and an additive. In embodiments, the ink compositioncomprises (or consists of) a solvent system; resin particles; acolorant; a wax; and optionally, an additive. In any of theseembodiments, the additives may be selected from a stabilizer, asurfactant, an anti-foam agent, a defoamer, a wetting agent, and abiocide. In any of these embodiments, the components may be selectedfrom any of the solvent systems, resin particles, colorants, waxes, andadditives disclosed herein. In any of these embodiments, amounts of thecomponents may be used as described above.

The aqueous inkjet ink compositions may be formed by combining thedesired components at the desired amounts and mixing. An illustrativemethod comprises adding any of the disclosed latexes (or the resinparticles) to a colorant dispersion to form a first mixture; and addinga second mixture comprising a solvent system and an additive(s) to thefirst mixture to form the aqueous inkjet ink composition. A thirdmixture comprising a wax may be added to the combined first and secondmixtures. Mixing and/or heating may be used during the method. Theaqueous inkjet ink composition may be filtered prior to use.Illustrative details are provided in the Examples, below.

Properties

The aqueous inkjet ink compositions may be characterized by variousproperties, including properties which indicate that the composition iscapable of being used in an inkjet printing apparatus to form printedimages. The aqueous inkjet ink compositions may be characterized by aninitial viscosity (measured within a day of forming the ink, at 37° C.,and over a frequency range of from 1 to 6.3 s⁻¹ or 40 to 400 s⁻¹). Theinitial viscosity may be in a range of from 1 to 15 cP, which includesfrom 2 to 10 cP and from 3 to 8 cP. Such values distinguish the aqueousinkjet ink composition from other compositions, e.g., paints, which havesignificantly higher initial viscosities, e.g., more than 50 cP.

The aqueous inkjet ink compositions may be characterized by their waterfastness. Wet rub resistance, measured as described in the Examplesbelow, provides a measure of water fastness. In embodiments, the aqueousinkjet ink composition exhibits a wet rub resistance of at least 10, 12,or 14 as measured using an about 4.5 ng drop of the ink or a wet rubresistance of at least 15, 17, or 19 as measured using an about 9 ngdrop of the ink. These values may refer to water fastness on papersubstrates. As demonstrated in the Examples below, illustrative aqueousinkjet ink compositions exhibit even greater water fastness on metalsubstrates, e.g., aluminum, including a wet rub resistance of at least30 as measured using an about 9 ng drop of the ink.

The aqueous inkjet ink compositions may be characterized by theiropen-air stability. The time before gelation in the aqueous inkjet inkcomposition upon exposure to air is observed provides a measure of suchstability. This time may be determined as described in the Examples,below. In embodiments, the time before gelation is greater than 3 hours,greater than 4 hours, or in a range of from 3 hours to 5 hours. Asdemonstrated in the Examples, the time before gelation was extended byabout 100% for an illustrative aqueous inkjet ink composition ascompared to comparative aqueous inkjet ink compositions comprising resinparticles formed from monomers which did not include a phosphoric acidmonomer.

The aqueous inkjet ink compositions may be characterized by theirlong-term stability. Comparing an initial viscosity of the aqueousinkjet ink compositions (measured within a day of forming the ink) toviscosity values of the inks after storage at an elevated temperature(e.g., 60° C.) for a period of time (e.g., 3, 7, or 14 days) provides ameasure of such stability. As demonstrated in the Examples, illustrativeaqueous inkjet ink compositions exhibit viscosity values (measured at37° C. and over a frequency range of from 1 to 6.3 s⁻¹ or 40 to 400 s⁻¹)after storage at 60° C. for 14 days that are within ±5% of respectiveinitial viscosity values.

The aqueous inkjet ink compositions may be used to form printed images.In embodiments, such a method comprises ejecting droplets of any of thedisclosed aqueous inkjet ink compositions onto a substrate to form animage thereon. The image may be of any form, e.g., text, graphic, etc.Such a method may further comprise incorporating the ink compositioninto an inkjet printing apparatus. The printing apparatus may employ athermal inkjet process wherein the ink composition in the nozzles isselectively heated in an imagewise pattern, thereby causing droplets ofthe ink composition to be ejected in imagewise pattern. Alternatively,the printing apparatus may employ an acoustic inkjet process whereindroplets of the ink composition are caused to be ejected in imagewisepattern by acoustic beams. In yet another embodiment, the printingapparatus may employ a piezoelectric inkjet process, wherein droplets ofthe ink composition are caused to be ejected in imagewise pattern byoscillations of piezoelectric vibrating elements.

The method may comprise ejecting ink droplets in an imagewise patternonto an intermediate transfer member, heating the image to partially orcompletely remove solvents, and transferring the ink composition in theimagewise pattern from the intermediate transfer member to a finalrecording substrate. The intermediate transfer member may be heated to atemperature above that of the final recording sheet and below that ofthe ink composition in the printing apparatus. An offset or indirectprinting process is also disclosed in, for example, U.S. Pat. No.5,389,958, the disclosure of which is totally incorporated herein byreference.

Any suitable substrate or recording sheet can be employed as the finalrecording sheet. It is a feature of at least embodiments of the aqueousinkjet ink compositions that they are printable on both paper andnon-paper, e.g., metal substrates. Metal substrates include, e.g.,aluminum, brass, stainless steel, and copper. The substrates havingimages printed thereon using the any of the disclosed aqueous inkjet inkcompositions are also encompassed by the present disclosure.

EXAMPLES

The following Examples are being submitted to further define variousspecies of the present disclosure. These Examples are intended to beillustrative only and are not intended to limit the scope of the presentdisclosure. Also, parts and percentages are by weight unless otherwiseindicated. As used herein, “room temperature” refers to a temperature offrom about 20° C. to about 25° C.

Examples 1-4

A reactive surfactant solution of 1.2 grams (Hitenol AR 1025 fromMontello) and 35 grams deionized water was prepared by mixing in a glassreactor. The reaction was then purged with nitrogen for 30 minutes. Thereactor was then continuously purged with nitrogen while being stirredat 250 rpm. The reactor was then heated to 75° C. and held there.Separately, 0.3 grams of ammonium persulfate (APS) initiator wasdissolved in 5 grams of deionized water and added to the reactor.

Separately, a monomer emulsion was prepared in the following manner:styrene, butyl acrylate, methacrylic acid, phosphoric acid2-hydroxyethyl methacrylate ester (PAM) (Examples 1,4),bis[2-(methacryloyloxy)ethyl] phosphate (B2MP) (Examples 2, 3, 4),Glycerol formal methacrylate (Glyfoma) (Example 3), 1-dodecanethiol(DDT), poly(ethylene glycol) diacrylate (PEGDA250) (Example 1), HitenolAR 1025, and deionized water were mixed to form an emulsion. The amountsof these components used are shown in Table 1, below. The emulsifiedmixture was fed to the reactor slowly for 2 h and the reaction continuedfor 2 h. An additional 0.15 g of APS initiator was dissolved indeionized water and added to the reactor over 10 minutes and thereaction continued for an additional 1.5 hours. The resulting latex wascooled to room temperature and neutralized to pH 8.0 with either 30%aqueous solution of dimethylethanolamine (DMEA) or 5 M KOH solution topH 5.0 and from pH 5 to 8 with 30% DMEA.

The latex formulations are shown in Table 1.

In replicate experiments, in order to carry out seeded microemulsionpolymerization instead of seed-free, 5% of the monomer emulsion was fedto the reactor over 10 min, followed by the addition of APS in 10 min.The mixture was held at constant temperature for an additional 10 minand the remaining monomer emulsion was fed in to the reactor over 2 h.The subsequent steps were followed as described above for seed-freeemulsion polymerization.

Example 5-7 (Comparative)

In these examples, the procedure of Examples 1-4 was repeated but usinga different mixture of monomers as shown in Table 1. Specifically, nophosphoric acid monomer was used. Instead, hydrophilic monomers wereused such as sodium 4-styrenesulfonate (4-NaSS) and in Example 5,hydroxyethyl acrylate (HEA). Colloidal silica was also used in Example5. The latex formulations are shown in Table 1.

TABLE 1 Latex Formulations. Comparative Comparative Comparative Material(g) Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example7 Styrene 24 24 22 22 28 23 24 Butyl Acrylate 11 11 12 12 7 11 12Methacrylic Acid 3.5 3.8 3.5 3.6 3 3 3 Reactive Surfactant 1.9 1.9 1.91.9 1.8 1.8 1.9 PAM 1.5 0 0 1.6 0 0 0 B2MP 0 1.5 1.1 1.1 0 0 0 Glyfoma 00 1.7 0 0 2 0.5 4-NaSS 0 0 0 0 1 1 0.5 HEA 0 0 0 0 1.25 0 0 PEGDA 2500.3 0 0 0 0.25 0.3 0.3 DDT 0.4 0.4 0.4 0.4 0.5 0.45 0.35 ColloidalSilica 0 0 0 0 0.75 0 0 APS 0.4 0.4 0.4 0.4 0.45 0.45 0.45 Deionizedwater 57 57 57 57 56 57 57 Total 100 100 100 100 100 100 100

Examples 8-15

Aqueous inkjet ink compositions were formed using the latexes ofExamples 3 and 4 and Comparative Examples 5-7. Specifically, aqueousinkjet ink compositions Examples 8-11 were formed using the latex ofExample 3 in CMYK colors. Aqueous inkjet ink compositions ComparativeExamples 12-15 were formed using the latex of Comparative Example 5 inCMYK colors. An aqueous inkjet ink composition Example 16 was formedusing the latex of Example 3 and a black pigment; this ink was used toprint on both metal and paper substrates. An aqueous inkjet inkcomposition Example 17 was formed using the latex of Example 4 and ablack pigment; this ink was used in the open-air stability studydescribed below. Aqueous inkjet ink compositions Comparative Examples 18and 19 were formed using the latex of Comparative Example 5 and blackpigment dispersions; these inks also contain a chelating agent (EDTA).Aqueous inkjet ink compositions Comparative Examples 20 and 21 wereformed using the latex of Comparative Examples 6 and 7, respectively anda black pigment; these inks were used in the open-air stability studydescribed below. The following steps were used to form the aqueousinkjet ink compositions and the formulations are shown in Table 2:

1. The pigment dispersion was added to deionized water and mixed forabout 15 minutes at a speed of about 650 RPM, using a Cowles bladeimpeller.

2. The latex was added slowly to the pigment dispersion and mixed forabout 20 minutes (Mixture A).

3. In a separate beaker, the co-solvents and additives (humectant,stabilizer, defoamer/antifoam, surfactant, wetting agent, and adhesionpromoter) were mixed to form a homogenous mixture (Mixture B).

4. Mixture B was slowly added into Mixture A. Once the addition wascomplete, the components were allowed to mix for another 20 minutes.

5. The wax was added and mixing continued for about another 15 minutes.

6. After mixing, the aqueous inkjet ink composition was left at roomtemperature for about 60 minutes before checking pH, conductivity andsurface tension.

TABLE 2 Aqueous Inkjet Ink Compositions Component Chemical 8 9 10 11 1213 14 15 16 17 18 19 20 21 Solvent Water 25.5 8.8 22.5 20.6 24.5 8 20.918.5 20.3 20.9 14.5 12.5 20.1 20.0 Pigment C = cyan, 31.5 55 36 36.531.5 55 36 36.5 33 36.5 36.5 36.5 36.5 36.5 M = magenta (C) (M) (Y) (K)(C) (M) (Y) (K) (K) (K) (K) (K) (K) (K) Y = yellow K = black Latex Latexof Example 3 8.9 7.5 7.7 8 — — — — 14 — — — — — (41.6%) Latex of Example4 — — — — — — — — — 8.7 — — — — (39.5%) Latex of Comparative — — — —11.4 9 9.5 10.2 — — 10.2 10.2 — — Example 5 (32.15%) Latex ofComparative — — — — — — — — — — — — 8.55 — Example 6 (38.3%) Latex ofComparative — — — — — — — — — — — — — 8.7 Example 7 (37.8%) Defoamer/BKY024/ 0.3 — 0.3 0.2 0.3 — 0.3 0.2 0.3 0.2 0.2 0.2 0.2 0.2 AntifoamFoamStar 2434 Co-solvent 1 Propylene glycol 15 14.5 23 17.5 13.5 14.2 2317.3 8.5 16 17.3 17.3 17.2 17.3 Co-solvent 2 1,4-butanediol 9 — 2 7.5 9— 2 7 14 8 7 7 7 8 Co-solvent 3 1,2-hexanediol 4 8 2 4 4 7.6 2 5 4 4 5 55 4 Humectant Glycerol 4 4 4 4 4 4 4 4 4 4 4 4 4 4 StabilizerMonoethanolamine/ 0.06 0.15 0.05 0.05 0.05 0.13 0.05 0.05 0.1 0.05 0.050.05 0.2 0.05 Triethanolamine Wetting Multifunctional 0.67 1 0.9 0.60.75 1 0.75 0.3 0.6 0.62 0.3 0.3 0.3 0.3 Agent nonionic surfactantSurfynol AD01/ Hydropalat WE 3650 Surfactant Tego Tween 4000 0.03 0.030.03 0.03 0.03 0.03 0.03 0.03 0.01 0.03 0.03 0.03 0.03 0.03 AdhesionBYK4500 — — — — — — — — 1.2 — — — — — Promoter Chelating Aqueous EDTA —— — — — — — — — — 4 6 — — Agent (0.5%) Wax Michem Lube 190 1 1 1.5 1 1 11.5 1 — 1 1 1 1 1 (35% solids) Total % 100

Print Testing

The aqueous inkjet ink compositions were jetted using a Dimatix DMP2800printer on four different paper substrates, including, McCoy® gloss#100, SUW Matte, Xerox® Bold, and Kodak photo paper. A first set of testkey parameters used were as follows: Drop mass=4.5-4.8 ng (i.e., about4.5 ng), Drop velocity=6-7 m/s, frequency=5 kHz, voltage=16-20 V,printing temperature was 20° C. to 40° C. A second set of test keyparameters used were as follows: Drop mass=8.5-9 ng (i.e., about 9 ng),Drop velocity=9-11 m/s, frequency=5 kHz, voltage=24-27 V, printingtemperature was 20° C. to 40° C. The print parameter was a 600×600 dpiprint. The measurement was done using a PIAS II instrument, which is apersonal image analysis system with a digital loupe. The high-resolutionoptic module ˜5 μm/pixel was used which has a field view of ˜3.2 mm×2.4mm to measure the dot size and diameter. Aqueous inkjet ink compositionswhich passed continuous jetting for >10-30 minutes were considered toexhibit good latency. The results are shown in Table 4 and discussedfurther below.

Metal Binding Testing of Latexes

An aqueous solution of CaCl₂(10 mM) was prepared with deionized water.Aliquots of latexes from Examples 3 and 4 (1.25 g, neutralized withKOH+DMEA) were mixed with calcium chloride solution (8.75 g) to make 5%latex dispersion. The dispersions were mixed overnight at roomtemperature. The next day, the latex dispersions were washed with Amiconcentrifuge filter units (100,000 molecular weight cut off (MWCO))extensively to remove all non-bound calcium ions (at least 10 times, 30min, 4000 rpm). The recovered samples were immersed in liquid nitrogenand freeze-dried overnight. This process formed fine powders without anysign of aggregation. The dried latex particles were then digested in amixture of nitric and hydrofluoric acid and tested for Ca ions usingInductively Coupled Plasma (ICP). The results are discussed furtherbelow.

Open-Air Stability of Latexes

The stability of the aqueous inkjet ink compositions in open air wasstudied with the visual assessment of the onset of structure formation(gelling), the state of gelation, and fully gelled ink. For each study,4 grams of test ink(s) along with a control ink were dispensed inidentical Pyrex Petri dishes (60 mm d, 10 mm h) in the lab space (32%relative humidity, 22° C.) and inspected every 30 minutes for a totaltest duration of 5 hours. At each inspection interval, ink dishes weregently swirled to assess the severity of structure formation. Due to thevariation in temperature, humidity, and air flow in the testenvironment, the weight of each sample was also measured. For eachmeasurement, reported times for onset of gelation were corrected to 5.5weight % evaporation per hour. The results are discussed further below.

Wet Rub Resistance (Water Fastness)

Aqueous inkjet ink compositions were tested for wet rub resistance (20double-rubs using wet Q-tip) (water fastness). Drops (4.5 and 9 ng) ofeach aqueous inkjet ink composition were printed on the desiredsubstrate. The numbers in Table 4 indicate the number of double-rubs (anaverage of 3 measurements) that were obtained before any removal of theink was observed. The results are shown in Table 4 and discussed furtherbelow.

Results

The four paper substrates used for printing were studied using theEnergy Dispersive X-ray (EDX) feature on an electron microscope. Theresults are shown in Table 3, demonstrating that all four substratescontain a high amount of metal (calcium and aluminum). The ICP resultsalso showed that the latexes of Examples 1-4 showed strong chelationability. For example, the latex of Example 4 showed ˜4000 ppm calciumion uptake while a control latex (the latex of Example 4 without calciumion incubation) only showed 3 ppm of calcium uptake.

TABLE 3 Metal content of various paper substrates. Paper Substrate C (%)O (%) Ca (%) Al (%) McCoy ® gloss #100 14.1 42.2 28.7 2.5 SUW Matte 11.744.5 20.4 6.7 Xerox ® Bold 31.1 51.9 5.9 <1 Kodak photo paper 9.1 47.3<1 34.2

As shown in Table 4, aqueous inkjet ink compositions Examples 8-11showed excellent jetting (no misdirectionality and satellites, jettedfor >30 minutes), latency, and decap time. These also showed improvedwater fastness (both at about 4.5 ng and about 9 ng drop mass) andmechanical properties as compared to aqueous inkjet ink compositionsComparative Examples 12-15 and other commercial benchmark inks.

TABLE 4 Printing Performance and Water Fastness of Aqueous Inkjet InkCompositions. Example 8 Example 9 McCoy Gloss SUW Matte McCoy Gloss SUWMatte Drop mass 4.5 9 4.5 9 4.5 9 4.5 9 (ng) Dot 50.40 61.23 54.53 65.0353.50 68.60 63.10 79.93 Diameter (μm) Dot 1.00 1.00 1.00 1.00 1.00 1.101.10 1.20 Circularity Mottle 0.30 0.17 0.33 0.20 0.50 0.37 0.47 0.37Graininess 2.47 0.60 2.00 0.47 2.17 0.23 2.27 0.47 Line 0.046 0.0600.050 0.064 0.046 0.067 0.060 0.079 Width (mm) OD 1.17 1.68 1.25 1.650.99 1.58 0.96 1.53 L* 58.79 48.16 57.01 48.51 57.37 47.74 57.64 47.94a* −31.80 −28.60 −34.33 −31.48 66.48 77.09 63.80 75.46 b* −50.81 −58.65−48.55 −55.83 −13.13 −3.42 −11.43 −2.73 Water 14 19 — — 12 16 — —fastness (rub) Example 10 Example 11 McCoy Gloss SUW Matte McCoy GlossSUW Matte Drop mass 4.5 9 4.5 9 4.5 9 4.5 9 (ng) Dot 52.07 64.03 53.5768.70 58.13 70.00 63.20 79.87 Diameter (μm) Dot 1.00 1.00 1.10 1.07 1.001.00 1.10 1.10 Circularity Mottle 0.40 0.30 0.40 0.23 0.73 0.60 0.700.47 Graininess 2.47 0.70 2.13 1.20 2.63 0.40 2.37 0.90 Line 0.048 0.0640.050 0.067 0.055 0.069 0.061 0.080 Width (mm) OD 0.88 1.13 0.88 1.091.15 1.66 1.08 1.56 L* 91.55 90.84 90.86 89.77 31.98 16.41 34.53 18.97a* −7.58 −5.45 −7.83 −5.67 1.40 0.81 1.37 0.66 b* 88.17 104.19 87.04100.00 1.34 −1.35 2.52 −1.22 Water 12 18 — — 14 19 — — fastness (rub)Comparative Example 12 Comparative Example 13 McCoy Gloss SUW MatteMcCoy Gloss SUW Matte Drop mass 4.5 9 4.5 9 4.5 9 4.5 9 Dot 53.33 63.3760.67 74.33 62.13 68.63 67.70 75.30 Diameter (μm) Dot 1.00 1.00 1.201.20 1.00 1.00 1.20 1.20 Circularity Mottle 0.53 0.30 0.53 0.30 0.570.40 0.57 0.37 Graininess 3.70 1.60 2.87 1.50 2.10 1.10 1.73 1.27 Line0.048 0.063 0.058 0.073 0.057 0.066 0.063 0.075 Width (mm) OD 1.03 1.551.04 1.53 1.03 1.42 1.01 1.34 L* 60.85 49.85 60.95 50.10 56.84 49.6056.85 50.49 a* −28.70 −28.61 −31.80 −30.95 67.91 75.09 65.40 72.84 b*−48.54 −57.37 −45.16 −54.45 −13.35 −5.94 −11.36 −5.62 Water 11 14 — — 1013 — — fastness (rub) Comparative Example 14 Comparative Example 15McCoy Gloss SUW Matte McCoy Gloss SUW Matte Drop mass 4.5 9 4.5 9 4.5 94.5 9 Dot 53.90 63.63 57.33 73.87 57.43 68.33 63.80 79.50 Diameter (μm)Dot 1.00 1.00 1.00 1.10 1.00 1.00 1.10 1.10 Circularity Mottle 0.40 0.330.40 0.30 0.70 0.60 0.63 0.53 Graininess 3.00 0.80 1.97 1.00 3.57 0.732.17 0.77 Line 0.050 0.065 0.058 0.074 0.051 0.063 0.062 0.081 Width(mm) OD 0.87 1.11 0.86 1.11 1.09 1.58 1.12 1.45 L* 91.68 90.74 90.7889.67 34.13 18.40 32.86 22.07 a* −7.68 −5.57 −8.33 −6.10 1.36 0.68 1.340.60 b* 87.81 103.17 85.57 101.16 0.72 −0.98 1.73 −0.50 Water 9 13 — — 912 — — fastness (rub)

Notably, aqueous inkjet ink compositions Examples 11 and 17 showedsubstantially improved open-air stability as evidenced by extended flowtime and delay in the onset of structure formation (gelling) underopen-air conditions. Specifically, the onset of gelation for thecomparative aqueous inkjet ink compositions Comparative Examples 15 and20 exhibited an onset of gelation in the 2 to 2.5 hour time range, whilethose of Examples 11 and 17 exhibited an onset of gelation of greaterthan 4.5 hours. This is an almost 100% improvement.

Additional experiments were performed to assess redispersion propertiesand long-term stability of the aqueous inkjet ink compositions.Regarding redispersion properties, 20 μL of aqueous inkjet inkcompositions Examples 8-11 and commercial inks were placed in Petridishes and dried at room-temperature for 5 days. The ink co-solventmixture (7 mL) was then gently added to each dish and the dishes wereleft undisturbed for 45 min. Visual assessment was used to evaluateredispersion by observing the extent of the spread of the colored inksin the co-solvent mixture. Aqueous inkjet ink compositions Examples 8-11spread quickly, with noticeable dispersion at 15 minutes and nearlycomplete dispersion at 45 minutes. The commercial inks dispersed muchmore slowly. Their spread was about half that of aqueous inkjet inkcompositions Examples 8-11 at 45 minutes. Finally, after rinsing withsolvents, aqueous inkjet ink compositions Examples 8-11 did not leaveany ring behind but the commercial inks left a drying ring for CMYcolors.

Regarding long-term stability, aqueous inkjet ink compositions weresubjected to accelerated aging tests at 60° C. At various time points asshown in Table 5, below, the viscosity of the aqueous inkjet inkcompositions was measured at 37° C. and over two frequency ranges usingan Ares G2 by TA instruments. The results show that the viscosity of theaqueous inkjet ink composition Example 11 is nearly unchanged after 14days at 60° C. (within 3.8% and 2.9% of the initial viscosity values atthe first and second frequency ranges, respectfully). These results alsoconfirm that the resin particles of the latex, from which the aqueousinkjet ink composition Example 11 was formed, are freely dispersedthroughout the ink and not adsorbed, attached, or coated onto thecolorant in the composition. By contrast, aqueous inkjet inkcompositions Comparative Examples 18 and 19 show severe instability.

TABLE 5 Rheological Stability of Aqueous Inkjet Ink CompositionsViscosity at Viscosity at T = 37° C. and T = 37° C. and from 1 to 6.3s⁻¹ from 40 to 400 s⁻¹ (% change from (% change from Example Day Day 0)Day 0) Example 11 0 (initial viscosity 3.70 3.84 value) Aged 3 days @3.72 (0.54%) 3.84 (0%) 60° C. Aged 7 days @ 3.69 (0.27%) 3.78 (1.6%) 60°C. Aged 14 days @ 3.84 (3.8%) 3.95 (2.9%) 60° C. Comparative 0 (initialviscosity 3.72 3.85 Example 18 value) Aged 3 days @ 7.85 (110%) 7.42(93%) 60° C. Comparative 0 (initial viscosity 3.45 3.83 Example 19value) Aged 3 days @ 10.87 (215%) 7.59 (98%) 60° C.

Finally, printing tests were carried out to demonstrate that the aqueousinkjet ink compositions based on the latexes of Examples 1-4 were ableto be printed on non-paper substrates, including metal substrates. Forexample, aqueous inkjet ink composition Example 8 was successfullyprinted on aluminum, brass, stainless steel and copper. Additional printtesting was conducted by printing aqueous inkjet ink composition Example16 on aluminum. Microscopic images of dots, lines, and solid blockprinted using this ink showed good spread. A dot diameter of 51 μm and aline width of 47 μm was obtained. In addition, the print on aluminum wasexceptionally durable and resistant to both dry and wet rubs. The waterfastness results using an about 9 ng drop size exceeded 30 double-rubs(virtually perceived infinite water fastness). By contrast, a commercialink dissolved in the wet cotton swab within the first 3 double-rubs.

The word “illustrative” is used herein to mean serving as an example,instance, or illustration. Any aspect or design described herein as“illustrative” is not necessarily to be construed as preferred oradvantageous over other aspects or designs. Further, for the purposes ofthis disclosure and unless otherwise specified, “a” or “an” means “oneor more.”

If not already included, all numeric values of parameters in the presentdisclosure are proceeded by the term “about” which means approximately.This encompasses those variations inherent to the measurement of therelevant parameter as understood by those of ordinary skill in the art.This also encompasses the exact value of the disclosed numeric value andvalues that round to the disclosed numeric value.

The foregoing description of illustrative embodiments of the disclosurehas been presented for purposes of illustration and of description. Itis not intended to be exhaustive or to limit the disclosure to theprecise form disclosed, and modifications and variations are possible inlight of the above teachings or may be acquired from practice of thedisclosure. The embodiments were chosen and described in order toexplain the principles of the disclosure and as practical applicationsof the disclosure to enable one skilled in the art to utilize thedisclosure in various embodiments and with various modifications assuited to the particular use contemplated. It is intended that the scopeof the disclosure be defined by the claims appended hereto and theirequivalents.

What is claimed is:
 1. A latex comprising water and resin particles, theresin particles comprising a polymerization product of reactantscomprising: one or more types of hydrophobic monomers; and one or moretypes of acidic monomers comprising one or more types of phosphoric acidmonomers, wherein a total amount of polymerized acidic monomers in theresin particles is at least about 8 weight % and a total amount ofpolymerized phosphoric acid monomers in the resin particles is at leastabout 2 weight %.
 2. The latex of claim 1, wherein the total amount ofpolymerized acidic monomers is at least about 10 weight %.
 3. The latexof claim 1, wherein the reactants do not comprise 4-methylstyrene,cyclohexyl acrylate, isobornyl methacrylate, isobornyl acrylate, orcombinations thereof.
 4. The latex of claim 1, wherein the one or moretypes of hydrophobic monomers comprise styrene and an alkyl(meth)acrylate.
 5. The latex of claim 1, wherein the reactants comprisea dioxane/dioxolane monomer that is an ester of (meth)acrylic acid withan alcohol comprising a dioxane moiety, an ester of (meth)acrylic acidwith an alcohol comprising a dioxolane moiety, or both.
 6. The latex ofclaim 5, wherein the one or more types of hydrophobic monomers comprisealkyl (meth)acrylate and polymerized alkyl (meth)acrylate is present inthe resin particles at an amount of least at about 15 weight %.
 7. Thelatex of claim 1, wherein the one or more types of phosphoric acidmonomers comprise those selected from the group consisting of P(O)(OR)₃,wherein each R is independently selected from hydrogen and an alkyl(meth)acrylate and at least one R is the alkyl (meth)acrylate; aphosphate ester of polyethylene glycol mono(meth)acrylate; a phosphateester of polypropylene glycol mono(meth)acrylate; and combinationsthereof.
 8. The latex of claim 1, wherein the one or more types ofphosphoric acid monomers comprise those having formula P(O)(OR)₃,wherein each R is independently selected from hydrogen and ethyl(meth)acrylate and at least one R is the ethyl (meth)acrylate.
 9. Thelatex of claim 1, wherein the one or more types of phosphoric acidmonomers comprise those selected from the group consisting of phosphoricacid 2-hydroxyethyl methacrylate ester, bis[2-(methacryloyloxy)ethyl]phosphate, and combinations thereof.
 10. The latex of claim 1, whereinthe one or more types of acidic monomers further comprise one or moretypes of additional acidic monomers.
 11. The latex of claim 10, whereina weight ratio of the total amount of polymerized phosphoric acidmonomers to a total amount of polymerized additional acidic monomers isless than about 0.8.
 12. The latex of claim 11, wherein the ratio isless than about 0.4.
 13. The latex of claim 10, wherein the one or moretypes of additional acidic monomers comprise methacrylic acid.
 14. Thelatex of claim 1, wherein the latex does not comprise a colorant. 15.The latex of claim 1, wherein the reactants do not comprise anunsaturated ethylene monomer having an alkyl group having from 12 to 22carbons.
 16. The latex of claim 1, wherein the latex does not compriseboric acid, diglycolic acid, a chelating agent, or combinations thereof.17. The latex of claim 1, wherein the one or more types of hydrophobicmonomers comprise styrene and an alkyl (meth)acrylate; the one or moretypes of phosphoric acid monomers comprise those selected from the groupconsisting of P(O)(OR)₃, wherein each R is independently selected fromhydrogen and an alkyl (meth)acrylate and at least one R is the alkyl(meth)acrylate; a phosphate ester of polyethylene glycolmono(meth)acrylate; a phosphate ester of polypropylene glycolmono(meth)acrylate; and combinations thereof; the one or more types ofacidic monomers further comprise one or more types of additional acidicmonomers; and the reactants further comprise a reactive surfactant. 18.The latex of claim 17, wherein the one or more types of additionalacidic monomers comprise methacrylic acid.
 19. The latex of claim 17,wherein the total amount of polymerized acidic monomers is at leastabout 10 weight % and a weight ratio of the total amount of polymerizedphosphoric acid monomers to a total amount of polymerized additionalacidic monomers is less than about 0.4.
 20. The latex of claim 1,wherein the one or more types of acidic monomers further comprise one ormore types of additional acidic monomers and wherein the total amount ofpolymerized acidic monomers in the resin particles is at least about 10weight % and a weight ratio of the total amount of polymerizedphosphoric acid monomers to a total amount of polymerized additionalacidic monomers is less than about 0.8.